Preclinical characterisation of gallium-68 labeled ferrichrome siderophore stereoisomers for PET imaging applications.

BACKGROUND: Siderophores are small iron-binding molecules produced by microorganisms to facilitate iron acquisition from the environment. Radiolabelled siderophores offer a promising solution for infection imaging, as they can specifically target the pathophysiological mechanisms of pathogens. Gallium-68 can replace the iron in siderophores, enabling molecular imaging with positron emission tomography (PET). Stereospecific interactions play a crucial role in the recognition of receptors, transporters, and iron utilisation. Furthermore, these interactions have an impact on the host environment, affecting pharmacokinetics and biodistribution. This study examines the influence of siderophore stereoisomerism on imaging properties, with a focus on ferrirubin (FR) and ferrirhodin (FRH), two cis-trans isomeric siderophores of the ferrichrome type. RESULTS: Tested siderophores were labelled with gallium-68 with high radiochemical purity. The resulting complexes differed in their in vitro characteristics. [68Ga]Ga-FRH showed less hydrophilic properties and higher protein binding values than [68Ga]Ga-FR. The stability studies confirmed the high radiochemical stability of both [68Ga]Ga-siderophores in all examined media. Both siderophores were found to be taken up by S. aureus, K. pneumoniae and P. aeruginosa with similar efficacy. The biodistribution tested in normal mice showed rapid renal clearance with low blood pool retention and fast clearance from examined organs for [68Ga]Ga-FR, whereas [68Ga]Ga-FRH showed moderate retention in blood, resulting in slower pharmacokinetics. PET/CT imaging of mice injected with [68Ga]Ga-FR and [68Ga]Ga-FRH confirmed findings from ex vivo biodistribution studies. In a mouse model of S. aureus myositis, both radiolabeled siderophores showed radiotracer accumulation at the site of infection. CONCLUSIONS: The 68Ga-complexes of stereoisomers ferrirubin and ferrirhodin revealed different pharmacokinetic profiles. In vitro uptake was not affected by isomerism. Both compounds had uptake with the same bacterial culture with similar efficacy. PET/CT imaging showed that the [68Ga]Ga-complexes accumulate at the site of S. aureus infection, highlighting the potential of [68Ga]Ga-FR as a promising tool for infection imaging. In contrast, retention of the radioactivity in the blood was observed for [68Ga]Ga-FRH. In conclusion, the stereoisomerism of potential radiotracers should be considered, as even minor structural differences can influence their pharmacokinetics and, consequently, the results of PET imaging.

Altruistic help or taking advantage of the situation? Social representations of surrogate motherhood.

Concerning Europe, the lay public, mainly in Central regions, still lacks information about what surrogacy is and how the process works in practice. It is one of the most controversial methods of assisted reproduction precisely because it goes against traditional social norms and ideas about the conception of life. The main aim of our study was to map the social representations of lay people that are formed in internet discussions. We focused on discussion forums over a time span of the last 10 years, from 2013 to 2022. We were also interested in whether perceived risks or benefits formed the core of social representations. Through a reflexive thematic analysis, we identified two distinct constructions of social representations of surrogacy, finding that value settings in terms of liberalism and conservatism appear to have the greatest influence on the anchoring and objectification of surrogacy.

[68Ga]Ga-Ornibactin for Burkholderia cepacia complex Infection Imaging Using Positron Emission Tomography.

Bacteria from the Burkholderia cepacia complex are generally considered to be non-pathogenic to the healthy population. However, some of these species may cause serious nosocomial infections in immunocompromised patients; as such, it is essential to diagnose these infections rapidly so that adequate treatment can be initiated. We report here the use of a radiolabeled siderophore, ornibactin (ORNB), for positron emission tomography imaging. We successfully radiolabeled ORNB with gallium-68 with high radiochemical purity and proved that the resulting complex has optimal in vitro characteristics. In mice, the complex did not show excessive accumulation in organs and was excreted in the urine. We demonstrated that the [68Ga]Ga-ORNB complex accumulates at the site of Burkholderia multivorans infection, including pneumonia, in two animal infection models. These results suggest that [68Ga]Ga-ORNB is a promising tool for the diagnosis, monitoring, and evaluation of the therapeutic response to B. cepacia complex infection.

Intergroup trust as a mediator between compassion and positive attitudes toward sexual minorities.

Nurturing compassion is not only beneficial for one's well-being in terms of feelings and cognitions directed toward oneself, but it can also have positive effects on attitudes toward other people through associated humanity and recognition of the universality of suffering. Having compassion toward others may be particularly beneficial in intergroup relations, as minority and stigmatized groups often experience a lack of compassion from the majority. The present study (N = 244) examines the relation between self-compassion, compassion toward others, and the level of trust and positive attitudes toward members of sexual minorities. The results of path analysis suggest that the relationship between compassion for others and attitudes toward people belonging to sexual minorities is mediated by intergroup trust. Fostering compassion could therefore play an important role in increasing trust and improving attitudes toward the people belonging to stigmatized minorities.

68Ga-labelled desferrioxamine-B for bacterial infection imaging.

PURPOSE: With the increase of especially hospital-acquired infections, timely and accurate diagnosis of bacterial infections is crucial for effective patient care. Molecular imaging has the potential for specific and sensitive detection of infections. Siderophores are iron-specific chelators recognized by specific bacterial transporters, representing one of few fundamental differences between bacterial and mammalian cells. Replacing iron by gallium-68 without loss of bioactivity is possible allowing molecular imaging by positron emission tomography (PET). Here, we report on the preclinical evaluation of the clinically used siderophore, desferrioxamine-B (Desferal®, DFO-B), radiolabelled with 68Ga for imaging of bacterial infections. METHODS: In vitro characterization of [68Ga]Ga-DFO-B included partition coefficient, protein binding and stability determination. Specific uptake of [68Ga]Ga-DFO-B was tested in vitro in different microbial cultures. In vivo biodistribution was studied in healthy mice and dosimetric estimation for human setting performed. PET/CT imaging was carried out in animal infection models, representing the most common pathogens. RESULTS: DFO-B was labelled with 68Ga with high radiochemical purity and displayed hydrophilic properties, low protein binding and high stability in human serum and PBS. The high in vitro uptake of [68Ga]Ga-DFO-B in selected strains of Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus agalactiae could be blocked with an excess of iron-DFO-B. [68Ga]Ga-DFO-B showed rapid renal excretion and minimal retention in blood and other organs in healthy mice. Estimated human absorbed dose was 0.02 mSv/MBq. PET/CT images of animal infection models displayed high and specific accumulation of [68Ga]Ga-DFO-B in both P. aeruginosa and S. aureus infections with excellent image contrast. No uptake was found in sterile inflammation, heat-inactivated P. aeruginosa or S. aureus and Escherichia coli lacking DFO-B transporters. CONCLUSION: DFO-B can be easily radiolabelled with 68Ga and displayed suitable in vitro characteristics and excellent pharmacokinetics in mice. The high and specific uptake of [68Ga]Ga-DFO-B by P. aeruginosa and S. aureus was confirmed both in vitro and in vivo, proving the potential of [68Ga]Ga-DFO-B for specific imaging of bacterial infections. As DFO-B is used in clinic for many years and the estimated radiation dose is lower than for other 68Ga-labelled radiopharmaceuticals, we believe that [68Ga]Ga-DFO-B has a great potential for clinical translation.

The Impact of Response Instruction and Target Group on the BIAS Map.

Response instructions-inviting participants to respond from a certain perspective-can significantly influence the performance and construct validity of psychological measures. Stereotype Content Model (SCM) and then the BIAS map ("behaviors from intergroup affect and stereotypes") were originally developed as universal measures of shared cultural stereotypes-participants' perceptions of what most of the people in a society think about the target group-and their related social-structural antecedents, emotions and behavioral tendencies. Yet a number of studies have adopted a different response instruction focusing on individual stereotypes-what the participants personally think about the target group. So far, there is little evidence to suggest how these two different response instructions (individual vs. shared cultural perspective) might influence the performance of the BIAS map, especially when applied to target groups that elicit different normative and social desirability concerns. To provide novel evidence, we conducted an experiment with a representative sample of ethnic Slovaks (N = 1269). In a 2 × 2 factorial design, we found response instruction (individual vs. shared cultural perspective) and target group [stigmatized ethnic minority (the Roma) vs. non-stigmatized ethnic minority (the Hungarians)] had significant effects on the BIAS map and their interaction had significant effects on the social structure and behavioral tendencies (but not on stereotypes and emotions) scales. Exploratory analysis also points to partial influence on the mediation hypothesis underlying the BIAS map and minor effects on its scale properties. Our evidence suggests that the difference between individual stereotypes and shared cultural stereotypes partially depends on the target group in question and that they should be treated as two potentially separate constructs.

Anti-roma Bias (Stereotypes, Prejudice, Behavioral Tendencies): A Network Approach Toward Attitude Strength.

The Roma have been and still are a target of prejudice, marginalization, and social exclusion across Europe, especially in East-Central European countries. This paper focuses on a set of stereotypical, emotional, and behavioral evaluative responses toward Roma people selected as representing the underlying components of anti-Roma bias. Employing network analysis, we investigated if attitude strength is associated with stronger connectivity in the networks of its constituent elements. The findings from representative surveys carried out in Hungary, Romania, Slovakia, France, and Ireland supported our assumption, as high attitude strength toward the Roma resulted in stronger connectivity in all pairs of high- versus low-attitude-strength networks. Our finding yields a solid theoretical framework for targeting the central variables-those with the strongest associations with other variables-as a potentially effective attitude change intervention strategy. Moreover, perceived threat to national identity, sympathy, and empathy were found to be the most central variables in the networks.

Head-To-Head Comparison of Biological Behavior of Biocompatible Polymers Poly(Ethylene Oxide), Poly(2-Ethyl-2-Oxazoline) and Poly[N-(2-Hydroxypropyl)Methacrylamide] as Coating Materials for Hydroxyapatite Nanoparticles in Animal Solid Tumor Model.

Nanoparticles (NPs) represent an emerging platform for diagnosis and treatment of various diseases such as cancer, where they can take advantage of enhanced permeability and retention (EPR) effect for solid tumor accumulation. To improve their colloidal stability, prolong their blood circulation time and avoid premature entrapment into reticuloendothelial system, coating with hydrophilic biocompatible polymers is often essential. Most studies, however, employ just one type of coating polymer. The main purpose of this study is to head-to-head compare biological behavior of three leading polymers commonly used as "stealth" coating materials for biocompatibilization of NPs poly(ethylene oxide), poly(2-ethyl-2-oxazoline) and poly[N-(2-hydroxypropyl)methacrylamide] in an in vivo animal solid tumor model. We used radiolabeled biodegradable hydroxyapatite NPs as a model nanoparticle core within this study and we anchored the polymers to the NPs core by hydroxybisphosphonate end groups. The general suitability of polymers for coating of NPs intended for solid tumor accumulation is that poly(2-ethyl-2-oxazoline) and poly(ethylene oxide) gave comparably similar very good results, while poly[N-(2-hydroxypropyl)methacrylamide] was significantly worse. We did not observe a strong effect of molecular weight of the coating polymers on tumor and organ accumulation, blood circulation time, biodistribution and biodegradation of the NPs.

Preclinical Evaluation of Radiolabeled Peptides for PET Imaging of Glioblastoma Multiforme.

In this study, we have compared four 68Ga-labeled peptides (three Arg-Gly-Asp (RGD) peptides and substance-P) with two 18F-tracers clinically approved for tumor imaging. We have studied in vitro and in vivo characteristics of selected radiolabeled tracers in a glioblastoma multiforme tumor model. The in vitro part of the study was mainly focused on the evaluation of radiotracers stability under various conditions. We have also determined in vivo stability of studied 68Ga-radiotracers by analysis of murine urine collected at various time points after injection. The in vivo behavior of tested 68Ga-peptides was evaluated through ex vivo biodistribution studies and PET/CT imaging. The obtained data were compared with clinically used 18F-tracers. 68Ga-RGD peptides showed better imaging properties compared to 18F-tracers, i.e., higher tumor/background ratios and no accumulation in non-target organs except for excretory organs.

The Influence of Feed-Supplementation with Probiotic Strain Lactobacillus reuteri CCM 8617 and Alginite on Intestinal Microenvironment of SPF Mice Infected with Salmonella Typhimurium CCM 7205.

Alginite is a non-ore raw material arising by fossilization of accumulated organic (algae) and inorganic material, particularly clay, carbonates, quartz, and amorphous modification of silicic acid in the aqueous environment. Humic acids as a component of organic portion of alginite are known for very good buffering ability which allows them to stabilise pH throughout the digestion system of animals, stimulate receptors of the immune system in intestinal villi against pathogenic bacteria, and support proliferation and activity of beneficial bacteria (lactobacilli, bifidobacteria, and similar). Our investigations focused on the influence of a probiotic strain in combination with alginite on intestinal microenvironment of SPF mice infected with Salmonella Typhimurium. The 66 female mice (BALB/c) used in our study were divided to four experimental groups, control NC1, control NC2 (alginite), IC (alginite + Salmonella Typhimurium CCM 7205NAL), LAB (Lact. reuteri CCM 8617 + alginite + Salm. Typhimurium CCM 7205NAL). The group supplemented with Lact.reuteri CCM 8617 and alginite showed significant reduction in growth of Salm. Typhimurium in mice faeces at 24 and 72 h (P < 0.001) post infection. The supplementation of additives affected positively also nitrogen, enzymatic, hepatic and energy metabolism of mice. The demonstrable positive influence of additives alleviated the negative impact of Salm. Typhimurium infection on the morphology investigated in the jejunum and ileum of LAB group of mice. The livers of mice treated with both alginite and Lact.reuteri CCM 8617 showed marked reduction of overall inflammation, hepatocyte necrosis and size of typhoid nodules.

Amoxicillin-clavulanic acid and ciprofloxacin-treated SPF mice as gnotobiotic model.

The experiment was carried out on 24 SPF BALB/c female mice and lasted for 15 days with a 5-day antibiotic (ATB) treatment and then 10 days without ATB treatment. The aim of our study was to acquire an animal model with reduced and controlled microflora and, at the same time, to ensure that the good health of these animals is maintained. Per oral administration of amoxicillin and clavulanate potassium in Amoksiklav (Sandoz, Slovenia) at a dose of 387.11 mg/kg body weight (0.2 ml of dilution per mouse) and subcutaneous administration of ciprofloxacin in Ciloxan (Alcon, Spain) at a dose of 18.87 mg/kg body weight (0.1 ml of dilution per mouse) were performed every 12 h during first 5 days of experiment. Five-day treatment with ATB led to a reduced survivability of microorganisms in faeces (28.33 ± 0.43 % on day 2) and caecum content (28.10 ± 1.56 %), where no cultivable microorganisms in faeces were present. Ten-day convalescence of decontaminated animals under gnotobiotic conditions prevented recovery of species diversity in mice gut microflora. This was reduced to two detectable cultivable species, namely Escherichia coli (GenBank KX086704) and Enterococcus sp. (GenBank KX086705) which were capable to restore its metabolic (CRL 2012) and morphological potential (Baratta et al. Histochem Cell Biol 131:713-726, 2009) within physiological range. Animals obtained under this procedure can be used in further studies. As a result, we created a mouse gnoto model with reduced and controlled microflora without alteration of the overall health status of the respective animals.

Analysis of biofilm formation by intestinal lactobacilli.

In this study, the biofilm-forming potential of intestinal Lactobacillus reuteri strains under different culture conditions was characterized by microtiter plate biofilm assays. Moreover, the spatial organization of exogenously applied L. reuteri L2/6 (a pig isolate) at specific locations in gastrointestinal tract of monoassociated mice was investigated by fluorescence in situ hybridization. We did not detect biofilm formation by tested strains in nutrient-rich de Man-Rogosa-Sharpe (MRS) medium. On the contrary, a highly positive biofilm formation was observed in medium with lower accessibility to the carbon sources and lack of salts. The results obtained confirmed the significant role of Tween 80 and the quantity and nature of the sugars in the growth medium in biofilm formation. The omission of Tween 80 in MRS medium favored the formation of biofilm. Abundant biofilm formation was detected in the presence of lactose, galactose, and glucose. However, a gradual increase in sugar concentration triggered a significant decrease in biofilm formation. In addition, conditions related to the gastrointestinal environment, such as low pH and the presence of bile and mucins, highly modulated biofilm production. This effect seems to be dependent on the specificity and properties of the medium used for cultivation. From the evidence provided by this study we conclude that the biofilm formation capacity of L. reuteri is strongly dependent on the environmental factors and culture medium used.

Constructions of sexual relationships: a study of the views of young people in Catalunia, England and Slovakia and their health implications.

Q methodology was applied to investigate the views of young people from Catalunia, England and Slovakia regarding sexual relationships and their health implications. The Q sorts of 188 16-18-year-olds from these three diverse European regions were reduced by Q factor analysis to six clear accounts. These accounts are presented in relation to three emergent themes: (a) traditionalism/liberalism; (b) locus of responsibility; and (c) the relationship between sex and love, and these discursive themes are discussed in relation to health-salient criteria such as awareness of sex-related risk and corresponding implications for conduct.